基于超弱光纤光栅的双芯带状柔性测斜光缆研究

Research on Dual-Core Flexible Belt Inclination Optic Fiber Based on Ultra-Weak Fiber Bragg Gratings

针对土木工程测斜传感器对柔性、灵敏度的需求,提出了一种基于超弱光纤光栅的双芯带状测斜光缆。基于切角递推的形变反演理论,建立了中心波长偏移量与光缆倾角的柔性测斜模型,通过仿真软件分析了光缆结构对传感器灵敏度的影响。基于仿真结果制备出双芯带状测斜光缆并进行了测试。结果表明,该光缆的测斜精度为182 pm/(°),实测倾角的最大相对误差为8.28%,应变传递效率约为裸光纤的88%,温度补偿误差小于4%。双芯带状测斜光缆克服了热加工中材料收缩对光纤的损伤,降低了现场环境温度的影响,实现了较高的测斜精度,在大尺度、高灵敏度的柔性测斜领域中具有广阔的应用前景。

Given the need for flexibility and sensitivity of civil engineering inclination sensors,a dual-core belt inclination optic fiber based on ultra-weak fiber Bragg grating is proposed.Based on the deformation inversion theory of tangent angle recursion algorithm,a flexible inclination model of central wavelength offset is established with respect to optical cable inclination angle.Furthermore,the influence of optical cable structure on the sensitivity of the sensor is analyzed via software simulation.Based on the simulation results,the dual-core belt inclination optic fiber optical cable is prepared and tested.The results show that the inclination accuracy of the optical cable is 182 pm/(°),the maximum relative error of the measured inclination angle is 8.28%,strain transfer efficiency is 88%,and temperature compensation error is less than 4%.The dual-core belt inclinometer optical cable structure overcomes the damage caused by material shrinkage on the optical fiber during thermal processing,reduces the influence of on-site ambient temperature,and exhibits high inclination accuracy.It has a broad application prospect in the field of large scale and high sensitivity flexible survey.